The invention relates to a multi-strand transverse flux machine with a unilateral stator and rotor, and having: essentially U-shaped yokes, that are assigned to the strands, and essentially I-shaped yokes arranged respectively alternately one behind the other in one plane in the stator with electrical annular windings; a rotor that is provided with permanent magnets that are attached planar to it surface adjacent to the yokes, with the rotor having a circular back iron; permanent magnets that are arranged in rows, mechanically displaced against each other; and currents that flow through the annular windings are electrically displaced accordingly. Such a transverse flux machine is known from the contribution of M. Bork and G. Henneberger "New Transverse Flux Concept for an Electric Vehicle Drive System," ICEM 1996.
Machines of this type can be constructed with an extremely high torque density. The machines are used in road vehicles or rail vehicles, preferably as direct drives that are built into the wheel hub. The range of use here extends from the passenger vehicle with single-wheel drive to locomotives and large utility vehicles. Other options for use are with stationary direct drives having a high constant output range, such as reeling drives and textile machines.
Transverse flux machines are for the most part embodied as two-strand machines because they have a dual stator arrangement, which does not allow for the realization of more than two strands with respect to production technology.
Known embodiments of two-sided transverse flux motors, e.g. as disclosed in the German Patent 44 43 999 A1 or the German Patent 195 22 382 A1, offer a high torque density, but can only be produced at high expense. These are contrasted by unilateral and also multi-phase transverse flux machines, which can be manufactured easily, but which have a considerably lower torque density because of the high rotor leakage (German Patent 195 32 614 A1).
The German Patent 36 02 268 A1 discloses a transverse flux machine, for which a right-angle bend of the legs for the U-shaped yoke is indicated. However, nothing is said about this measure in the text.
A different geometric design for a transverse flux machine is furthermore known from the European Patent 0 243 425, for which two side-by-side arranged U-shaped stator yokes are connected. Each half of the center leg in this case carries its flux. A possible savings potential is not indicated.
Known is furthermore the previously disclosed design by Bork and Henneberger of a transverse flux motor with unilateral stator and tangential back iron in the rotor. This solution also permits an embodiment with more than two strands because the individual strands can be lined up next to each other with a specific gap in between.
FIG. 1 accordingly shows a pole pair for a multi-pole arrangement. The p pole pairs can be lined up in a linear arrangement as linear motor and, in the case of an annular bending of the coil, can be embodied as rotatory machine. In the following, reference is made to a rotatory embodiment.
The active part of the machine stator consists of an annular winding 1 and a number p of essentially U-shaped, soft-magnetic yokes 2, which partially enclose the winding 1, as well as I-shaped soft-magnetic yokes 3 that are arranged in between the yokes 2. The U-shaped yokes 2 and the I-shaped yokes 3 can have a different width b.sub.u and b.sub.l for carrying the flux with varied intensity. The active part of the rotor for each strand consists of two annular rotor yokes 4 of a soft-magnetic material, to which are respectively attached 2p permanent magnets 5 with alternating radial magnetization. The torque-to-bore volume ratio of this embodiment is limited owing to the leakage path saturation.